**The Solar Furnace**

Objectives

A solar furnace is a system that combines a heliostat, a flat mirror that will orient itself toward the sun in order to reflect all the sun's available energy, and a parabolic mirror. The purpose of the solar furnace is to concentrate the maximum amount of radiation available in the focus of a parabolic mirror and to analyze the radiation's distribution within the thermal target.

Requirements

The system has been designed in order to reflect the sun's irradiance to a 1.15m diameter parabolic reflector and in order to fit the place assigned on the roof.

The system sustains wind load and the load due to its weight.

Optical analysis has been done in order to see the effects of tracker's errors in order to set a minimum precision.

The system includes a cooling system in order to remove all the heat entering the thermal target.

Mechanical design

Optical Analysis

Thermodynamics

Body

Project Development

Mechanical design

The first step in the development was to find

the size of the flat mirror using basic

trigonometry, sun’s vector and angles

Mechanical design

The next step after the size of the flat mirror

was to design the base support and to find the material

Technical data:

40x40 Typ C01-1

From :

KANYA SA

Neuhofstrasse 9

CH-8630 Rüti

Suisse

Tél: +41 55 251 58 58

Material :Alloy 6063

Ix=11.70 cm4

Iy=11.70 cm4

Wx=5.75 cm3

Wy=5.75 cm3

Profile surface=7.29 cm2

Weight=2.0 kg/m

Mechanical design

The goal was to find the highest possible

stability and for this reason solidworks analyses

have been done

Mechanical design

The next step was to decide the best way to hold the mirror.

Problem

Offset due to different axis rotation

Solution

Enlarge the frame size

Mirror cutting

Energy losses percentage:

1 - (Cutting Mirror Area / Full Mirror Area)*100=100-83.6=16.4%

It was decided to enlarge the size of the frame but it caused a bigger weight on the tracker

Mechanical design

displacement analysis

stress analysis

Mechanical design

System's connections

Optical Analysis

Optical Analysis

reflectors scattering

ideal case

Surface scattering: 1mrad

Surface scattering: 2mrad

Surface scattering: 3 mrad

Optical Analysis

tracking angles error

azimuth

elevation

In order to study and foresee the results and behavior of optical components of a system we carried out an optical simulation using OptiCAD software

Thermal target

Since the parabolic mirror concentrates all the sun irradiance on the termal target, we had to calculate the flow needed to remove the heat

Thermal target

Cooling system

In order to design the thermal target, we had to take into consideration a few factors as :

Dimension

Cooling

tubes

optics requirement

sensor's position

Thermal target

Ideal Size Receiver Calculation

In order to calculate the radius of the image, we first need to define the following measures:

• The aperture size D: is the index for amount of energy.

• Focal length F: is the index for image position.

• Rim angle : is the index for image size.

Thermal target

The ideal receiver has dimensions of 10 x 10 mm

Thermal target

The sensor hasn't been placed in the center

of the thermal target. We had to find the position of 30% of the maximum flux value

Thermal target

Mechanical design

HTF: Water

Heat Power on the Receiver: 830 W Required flow rate for cooling: 0.02 Kg/s Inlet water temperature in the receiver: 318 K Outlet water temperature in the receiver:328 K Flow Average Velocity: 0.84 m/s Convection coefficient : 3205 W/m^2K

Thermal target

Flow analysis

Heat Power on the receiver: 830 W Convection coefficient : 11 W/m^2 K Maximum surface temperature: 346 K

Thermal Analysis

Thermal target

Mechanical Analysis

The system satisfies environmental conditions, stability under wind load andself weight.

Optical Analysis

The energy that reaches the thermal target, while taking into account the mirror scattering is 830W.

The acceptable tracking error is 1 mrad.

The system will have an optical efficiency at least 51.18% .

Thermal analysis

The coolant flow rate required to remove the heat on the receiver is 0.02 kg/s.

Flow average velocity: 0.84 m/s

Maximum surface temperature: 346 K

Conclusion

Advisor: Maya Livshits

Ester Raccah

Jeremy Martiano

Michael Weitz

The system has been divided in two parts which are the heliostat (on the left side) and the parabolic mirror with a shutter and the thermal target (on the right side).

Mechanical design

Wind load analysis on the system

Mechanical design

Power :805 W

77%

Power : 683 W

66%

Power : 521 W

50%

21.06 12:00

Maximal Power :1038 W